Yeah, I don't think I'd be willing to alter the nose art. Kill marks are one thing, eliminating tail swastika markings, sure. But that nose art is basically the focal point of this skin - there aren't really any other elements. Wouldn't feel right to me to change it. As you say, there are plenty of other subjects that wouldn't be controversial.
I like to have visual cues from the cockpit to help me remember which skin I'm in, if I can. In the very old '38G skins I did, I had different pinup cards inside the cockpit.
Why did Zemke have a '38, anyway? Wasn't he the leader of the 56th FG, and didn't they fly P-47s exclusively? Was he really a member of S.A.P.P.?